Answer: Dimethylamine.
- A Dimethylamine
- B Methylamine
- C Trimethylamine
- D Aniline
Correct answer: A. Dimethylamine
Explanation: Dimethylamine (CH<sub>3</sub>)<sub>2</sub>NH has two methyl groups on nitrogen, making it secondary.
In aniline, the nitrogen's lone pair is pulled into the benzene ring through resonance, leaving less electron density available to accept a proton - which is why aniline is a much weaker base than methylamine, where the lone pair is fully available.
Concept context
Nitrogen-containing organic compounds. Covers classification (primary, secondary, tertiary), basicity comparison, preparation methods, and reactions including diazotization and coupling, key for understanding dyes and pharmaceuticals.